Managing a commercial greenhouse requires a two-pronged approach. Managing the business, on one hand, and managing the greenhouses on the other. Let’s get some dirt under our nails and talk about the greenhouses.
The three most important factors to manage are optimal temperature control, consistent air circulation, and proper moisture delivery. This can be more complex than you might expect, since different plants require specific (but different) soil temperatures or air temperatures at different stages of growth, including germination, flowering, and setting fruit.
Temperature Control
If a specific crop needs warmer soil for germination, consider using heating mats to raise the temperature on just those crops. If you’re trying to cool others down, consider setting up small shades over those specific flats.
- Be sure to open the greenhouse up before the weather gets too hot and close it before it’s too cool. It’s more expensive to catch up to the best temperature rather than easing into it naturally.
- Use external shade cloths or thermal blankets as needed during temperature extremes to help keep the interior at an acceptable temperature without blowing up the budget on electricity.
- Invest in good quality air and soil thermometers and check your conditions regularly. Slight changes in temperature and humidity can wreak havoc on your seedlings very quickly.
- If you can manage, and if the size of your operation warrants it, consider purchasing an automated temperature and ventilation system so it can make constant, minor adjustments throughout the day.
Air Circulation
Insects and fungi thrive in areas where air circulation is poor, creating pockets of humidity where mold and fungi thrive. Low vents along the side walls and end walls of your greenhouse to allow cool air in, while ridge vents permit warm air to escape. Fans along the ridge and along the short sides (end walls) can move air around the greenhouse and prevent spores and insects from getting comfortable on your seedlings.
Moisture Delivery
Seeds need moisture to germinate, but they don’t need deep watering since deep roots have not been established. Adjust your watering to keep a shallow zone with a high moisture content while allowing the very top layer of soil to dry occasionally.
Once the seedling begins to grow and extend its roots, deeper and longer but less frequent watering’s are called for. The cycle from wet to dry to wet encourages good root growth and allows the plant to become more tolerant to drought.
There are many irrigation models you can choose from to deliver moisture in your greenhouse. A more in-depth discussion can be found later in this series.
The Daily Grind
Some greenhouse management tasks need to be handled daily - perhaps first thing in the morning, as part of your getting started routine.
- Whenever possible, have the general manager or another specific experienced person tour your greenhouses every day to check on the health and development of your seedlings, the general health of your stock, over- or under- production, inventory levels, changes to the “feel” of any particular greenhouse, etc. A daily check should catch problems before they become serious, and it’s always good to have an overall “gut feeling” about your operations.
- Monitor daily weather forecasts and use those to manage your greenhouse climate. Cloudy summer day? Maybe you can forego those shade cloths for the day but keep an eye on the humidity, so you don’t let mildew get started.
- Don’t put tasks off - even the tedious or difficult ones. If it’s time to stake and prune your tomatoes, waiting until next week could make them so unwieldy with extra growth that you’ll need to cut them back and set back your yield accordingly.
- Scout for pests in your greenhouse weekly and be thorough. Respond at the first signs of an infestation, when the fix is relatively quick and effective. Once an infestation is fully established, it could take weeks and several expensive treatment repeats before the problem is under control. It is best to nip it in the bud.
Most importantly, do not panic. Things will go wrong. Just do what you can to salvage the situation, do a post-mortem to figure out what happened, and learn from it.
